Valuable clinical data concerning blood glucose variations can be obtained from continuous glucose monitoring. While periodic blood sampling is still used clinically to determine blood glucose, it is becoming apparent that continuous monitoring of blood glucose is important in the emergency and operating room and for the control of insulin pumps. The use of fiber optics in medicine has created an opportunity for developing biochemical sensors. Therefore, the objective of this bioengineering project is to test the feasibility of a new fiber optic sensor for in vivo blood glucose monitoring. The sensor is located at the tip of a dual fiber optic catheter which can be inserted into a blood vessel. The measurement is based on an attenuated total reflection technique and the principle of infrared absorption spectroscopy. We have successfully completed preliminary investigations in our laboratory using an experimental in vitro system which showed that we can measure glucose concentrations in water solutions and whole human blood with a standard error of estimate of 15 mg/d1 and 44 mg/d1, respectively. Based upon our pilot studies, we feel that it is important to investigate the feasibility of developing a catheter based fiber optic blood glucose sensor. The accuracy of the proposed fiber optic sensor will be improved by the application of multiple infrared wavelength analysis, similar to conventional analytical chemistry techniques. The fiber optic glucose sensor will be tested in flowing water and whole human blood in order to determine the accuracy and repeatability of the sensor for various concentrations of glucose. A limited number of animal investigations will also be performed to characterize the performance of the proposed sensor over the hypo- to hyperglycemic range. These pilot studies will enable us to seek additional support to perform more extensive animal and clinical investigations in the future.